Peelable labels are well known. They are constructed from a release liner upon which there is a release coating, an adhesive and a face stock. The face stock is releasably adhered to the release liner by contact with an adhesive located between the face stock and the release liner.
Typically the release liner is constructed by applying a release coating to one side of a plastic or paper liner sheet. Release coatings are characterized by an ability to strongly adhere to the liner sheet but weakly adhere to the adhesive which is located between the face stock and the liner.
The peelable label is converted into roll label stock by cutting the composite film with a die which only cuts through the face stock, not through the release liner, to form labels of specified shape. The surrounding face stock, known as the matrix, is peeled away from the release liner, leaving the labels adhered to the release liner which is then formed into a roll. The labels are usually dispensed by bending the roll stock to an angle which causes the label to lift away from the release liner. The label, released from the liner is then applied to a surface.
In composite films of this type, the release coating is usually made out of an electron beam curable composition which, typically includes a silicone resin having crosslinkable groups, such as acrylic residues. The silicone portion of the composition is the release agent which permits the adhesive to bond lightly to the release liner. The acrylic groups crosslink the release coating composition together and permit the release coating to form a strong bond to the surface of the liner sheet.
There are typically four levels of release force: premium release (10-15 g), easy release (20-40 g), high release (50-100 g) and tight release (&gt;100 g). For high speed label dispensing, the release liner should have a high release force. If the release force is too low, pre-dispensing occurs in which the labels fly off during die cutting rather than remain on the liner to form the roll stock.
Attempts to increase the release force by the addition of agents designed to strengthen the degree of release of the release coating cause unacceptable zippy noise, or zippiness, during matrix stripping and label dispensing. Zippy noise is an art-recognized term used to describe a jerking noise generated during the high speed matrix stripping process.